feat: add project-memory skill with OpenCode hook integration

Author: jacobjmc

.gitignore

@@ -32,3 +32,6 @@ public/assets/material-icons/
 
 # Nix
 result
+
+# Project memory (agent context)
+.memory/

.memory/SUMMARY.md

@@ -47,6 +47,17 @@
 - Agent/model selection from REST API
 - Incremental SSE streaming
 
----
-
-*Last updated: Session initialization*
+## Quick Stats
+
+- Total memories: 0
+- Last updated: 2025-02-24
+- Sessions since review: 0
+- Session tools available: true
+- Last bootstrap: 2025-02-24
+- Bootstrapped sessions: []
+- Project phase: foundation
+- Project phase epoch: 1
+- Close state: clean
+- Index dirty: false
+- Active session id: 2025-02-24-1
+- Last closed session id: ""

.opencode/opencode.json

@@ -0,0 +1,4 @@
+{
+  "$schema": "https://opencode.ai/config.json",
+  "plugin": ["./plugin/memory-hook.js"]
+}

.opencode/package-lock.json

@@ -0,0 +1,103 @@
+import * as fs from "node:fs";
+import * as path from "node:path";
+
+const SKILL_LOCATIONS = [
+  (dir) => path.join(dir, ".opencode", "skill", "project-memory", "SKILL.md"),
+  () =>
+    path.join(
+      process.env.HOME || process.env.USERPROFILE || "",
+      ".config",
+      "opencode",
+      "skill",
+      "project-memory",
+      "SKILL.md"
+    ),
+  () =>
+    path.join(
+      process.env.HOME || process.env.USERPROFILE || "",
+      ".claude",
+      "skills",
+      "project-memory",
+      "SKILL.md"
+    ),
+];
+
+function hasMemorySkill(projectDir) {
+  return SKILL_LOCATIONS.some((loc) => {
+    try {
+      return fs.existsSync(loc(projectDir));
+    } catch {
+      return false;
+    }
+  });
+}
+
+export const MemoryHook = async (ctx) => {
+  const loadedSessions = new Set();
+  const subagentSessions = new Set();
+
+  async function isSubagent(sessionID) {
+    if (subagentSessions.has(sessionID)) return true;
+    try {
+      const session = await ctx.client.session.get({ path: { id: sessionID } });
+      if (session.data?.parentID) {
+        subagentSessions.add(sessionID);
+        return true;
+      }
+    } catch {
+      return false;
+    }
+    return false;
+  }
+
+  return {
+    "chat.message": async (input, output) => {
+      if (!hasMemorySkill(ctx.directory)) return;
+      if (loadedSessions.has(input.sessionID)) return;
+      loadedSessions.add(input.sessionID);
+      if (await isSubagent(input.sessionID)) return;
+
+      const textPart = output.parts.find((p) => p.type === "text");
+      if (textPart?.text) {
+        textPart.text = `<system-reminder>Load project memory: read .memory/SUMMARY.md before starting work. If .memory/ doesn't exist, initialize it per the project-memory skill.</system-reminder>\n\n${textPart.text}`;
+      }
+    },
+
+    "tool.execute.after": async (input, output) => {
+      if (ctx.client.app?.log) {
+        await ctx.client.app.log({
+          body: {
+            service: "memory-hook",
+            level: "debug",
+            message: `tool.execute.after fired: tool="${input.tool}"`,
+          },
+          query: { directory: ctx.directory },
+        });
+      }
+
+      const toolLower = (input.tool || "").toLowerCase().replace("mcp_", "");
+      if (toolLower !== "todowrite") return;
+      if (await isSubagent(input.sessionID)) return;
+
+      const todos = input.args?.todos;
+      if (!Array.isArray(todos)) return;
+      if (!todos.some((t) => t.status === "completed")) return;
+
+      output.output += `\n\n<system-reminder>Task completed. If this work produced knowledge worth remembering (re-discovering would cost meaningful time), capture it to .memory/ following the project-memory skill. Only save decisions, patterns, bug root causes, or preferences — skip routine changes.</system-reminder>`;
+    },
+
+    "event": async ({ event }) => {
+      if (
+        event.type === "session.deleted" ||
+        event.type === "session.compacted"
+      ) {
+        const sid =
+          event.properties?.info?.id || event.properties?.sessionID;
+        if (sid) {
+          loadedSessions.delete(sid);
+          subagentSessions.delete(sid);
+        }
+      }
+    },
+  };
+};